Compressor apparatus



Sept. 5, 1967 R. F. CONNOR 3,339,829

COMPRESSOR APPARATUS Filed Sept. 2, 1965 2 Sheets-Sheet L Sem. 5, 1967 Filed Sept. 2, l

R. F. CONNOR COMPRESSOR APPARATUS 2 Sheets-Sheet Q United States Patent O 3,339,829 COMPRESSOR APPARATUS Ralph F. Connor, Evansville, Ind., assignor to Whirlpool Corporation, a corporation of Delaware Filed Sept. 2, 1965, Ser. No. 484,701 9 Claims. (Cl. 2311-17) This invention relates to Icompressor apparatus and in particular to means for preventing reverse rotation of a rotary compressor.

In one conventional form of refrigeration apparatus, a rotary compressor is employed for providing cornpressed refrigerant fluid as one step in the refrigeration cycle. In such rotary compressors, the compressor rotor is conventionally rotated by an electric motor mounted in the compressor housing. Also conventionally mounted in the compressor housing is a lubrication means driven by the electric motor and arranged to lubricate the moving parts of the compressor during operation. Such lubrication means conventionally are arranged to operate in a single direction of rotation so that in the event the electric motor is caused to rotate in a direction opposite to the preselected proper direction of rotation, a failure of the lubrication system will occur, quickly effecting serious damage to the mechanism. It has ybeen found that quite serious damage may occur to the compressor upon only two or three reverse rotations thereof. Thus, it is highly desirable to provide means for effectively precluding such undesirable reverse rotation of the compressor.

Even in rotary compressors having lubrication means arranged to operate in either direction of rotation, it is undesirable to have the driving motor inadvertently rotate opposite to the preselected proper direction. In an ordinary refrigeration system, such inadvertent reverse rotation of the driving motor would result in the eventual total lack of cooling effect at the evaporator surfaces as a result of the termination of refrigeration flow caused by the sealing of the discharge valves which, under these conditions, are subjected to a suction pressure. Thus, it is desirable to provide means for substantially immediately terminating the operation of the driving motor at such times when the motor is caused to rotate in a direction opposite tothe preselected proper direction.

Thus, a principal feature of the present invention is the provision of :a new and improved means for effectively and immediately stopping operation of a rotary compressor in the event of a reverse rotation thereof.

Another feature of the invention is the provision of such reverse rotation prevention means including means in the compressor housing for sensing the fluid pressure in the inlet to the compressor and in the space dened by the compressor housing, and control means responsive to the sensing means for stopping the motor in the event that the sensing means senses a fluid pressure in the inlet which is greater than the pressure within the housing space. K

Another feature of the invention is the provision of such a reverse rotation prevention means wherein the sensing means comprises a pressure responsive device having a Wall movable in response to the pressure differential between the interior of the housing and the inlet for effecting the desired control of the motor.

A further feature of the invention is the provision of such a reverserotation prevention means further including means for preventing back flow of the fluid from the compressor on reverse rotation.

Other features and advantages of theinvention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a schematic wiring diagram of the circuitry of -a compressor apparatus embodying the disclosed reverse rotation prevention means invention;

FIGURE 2 is a side partially sectional elevation of the compressor having portions broken away for facilitated illustration of the reverse rotation prevention means installed therein;

FIGURE 3 is a fragmentary enlarged vertical section illustrating a portion of the compressor as shown in FIGURE 2; and

FIGURE 4 is a fragmentary horizontal section taken substantially along the line 4 4 of FIGURE 3.

. In the exemplary embodiment of the invention disclosed in the drawing, a compressor generally designated 10 is' shown to comprise a rotary compressor such as for use in refrigeration apparatus having a suction conduit 11, for delivering refrigerant fluid to the compressor, and a first discharge conduit 12 for conducting compressed refrigerant fluid from the compressor. As shown in FIG- URE 2, the compressor includes -a -rotor 13 disposed in a pump cham-ber 14. The rotor 13 is carried on a shaft 15 driven by an electric motor 16. As shown in FIGURE 2, the compressor is hermetically enclosed within an outer housing 17 with the inlet 11 extending into the housing to have communication with the rotor chamber 14, and with the first discharge conduit 12 extending outwardly from the housing for conducting the compressed refrigerant fluid to a precooler coil 62 whereupon the compressed fluid is returned to the interior space 18 of the housing 17 through conduit 63. Thus, the fluid pressure within space or dome 18 is substantially the same as the pressure of the fluid leaving the compressor through first discharge conduit 12. Compressed fluid leaves space 18 through a second discharge conduit 64, connecting to ya condenser 65, which, in turn, is connected to a pressure reducing device 66. Device 66 is connected to evaporator coil 67, which connects to suction conduit 11 for fluid re-entry into the rotor chamber 14. The motor 16 is disposed within the upper portion of the interior space 18 of the housing 17 and is carried on a front head 19 in which the shaft 15 is journalled for rotation.

The front head 19 is carried on a rotor housing mem' ber 20, in turn, carried on a rear head 21 and a rear head cover 21a, all of which are supported on the bottom wall 22 of the housing 17 by means of a support member 23. The compressor is lubricated by means of a con-` .l ventional pump K 24 which circulates lubricating oil L from a lower sump portion 26 defined by the housing 17. The pump 24 draws oil from the sump 26 through an inlet opening 25 and pumps it upwardly through the shaft 15 through oil passages 15a therein for suitable lubrication of the rotating parts of the compressor. The pump 24 as shown herein, is of well known construction arranged to pump the lubricating oil in one direction of rotation of the motor 16 while being ineffective when the motor 16 is rotated in the opposite direction. For reasons stated above, the present invention is as equally desirable on those compressors or pumps of the type described in my aforementioned copending application, that is, compressors having lubrication means arranged to operate in either direction of rotation.

As discussed above, because of possible damage to the compressor and/ or the loss of cooling effect in the event the motor 16 is inadvertently operated opposite to the desired direction, it is advantageous to effectively prevent such undesirable reverse rotation. To this end, control apparatus generally designated 27 is provided for effectively stopping the motor 16 in the event of a reverse rotation thereof. More speciically, the reverse rotation prevention apparatus 27 in a preferred form comprises a pressure operated switch 37, as shown in FIGURE 3, having a movable contact 29 and fixed contacts 30 and 28. The movable contact 29 is carried by a switch member 36 of insulating material which is in turn supported on a wall member 31 of a bellows 32. The fixed contacts 28 and are carried on an insulated support 34 and are connected to electrical conductors 35 and 33, respectively. Thus, the bellows and support are electrically insulated from each other so that electrical connection between conductors 33 and 35 is effected when the contact 29 is in engagement with contacts 28 and 30, as shown in FIG- URE 3. As shown in FIGURE 1, the contacts 29, 28 and 30 comprise a normally closed switch 37 connected in series with an overload and/ or overheat switch 38, a conventional thermostat operated switch 70 for cycling the compressor in response to a temperature condition, and an operating coil 39 of a manual-reset contactor 40 having contacts 41, 42, and 43 connected to three-phase power supply lines L1, L2, and L3, respectively, for supply of three-phase power to the motor 16. Switch 37 and overload relay 38 are serially connected by means of electrical conductors 44 and 45 across the secondary 46 of a voltage stepdown transformer 47 having its primary winding 48 connected as shown across a pair of the power supply lines L1, L2, and L3. As shown in FIGURE 2, the conductors 35 and 45 are brought outwardly through a Wall of the housing 17 via suitable conventional hermetically sealed terminals 35a and 45a.

As shown in FIGURE 3, the exterior portion of the wall member 31 of the bellows 32 is in communication with a chamber 51 of inlet 11 through a passage 52 formed in the rotor housing member 20 and an aligned passage 53 formed in the front head 19. The interior space 50 of the bellows 32 communicates with the space 18 through a plurality of small openings 56 in support 34. During periods of compressor shut-down wherein the uid pressure within the space 18 is substantially equal to that Within inlet chamber 51, the bellows 32 is biased such that switch 37 is closed, that is, contacts 28, 29 and 30 are in electrical contact. Likewise, during periods of normal compressor operation wherein the fluid pressure within the space 18 greatly exceeds that pressure within inlet chamber 51, the bellows is in an extended position and switch 37 is closed. However, when the pressure of the refrigerant fluid in inlet chamber 51 exceeds the dome pressure, i.e., the pressure in space 18, the bellows 32 is actuated so as to move wall member 31 upwardly, as seen in FIGURE 3, thereby spacing contact 29 from fixed contact 30 and opening the circuit to the contacter coil 39, causing contacts 41, 42 and 43 to open. This immediately stops operation of the compressor motor 16 through interruption of its power supply by opening of the contacts 41, 42 and 43. The pressure of refrigerant fluid in inlet chamber 51 will exceed the pressure within the interior of the housing only upon a reverse rotation of motor 16 wherein the rotor 13 causes the pressurized refrigerant fluid to be delivered toward the inlet 11, rather than toward the outlet 12. The pressure build-up within chamber 53 such as to eiect opening of the switch 37 occurs within one or more cycles of reverse rotation of the compressor and thus the electric motor 16 is substantially immediately stopped, thereby effectively precluding damage to the compressor from a reverse operation thereof.

As best seen in FIGURE 3, the inlet 11 may be provided with a conventional lter 57 in an outer portion 11a thereof. The inlet passage is further defined by a turned portion 11b opening through an annular valve seat 58 in the chamber 51. The passage portion 11b is selectively closed by -means of a check valve disc 59 which during normal flow of refrigerant fluid through the inlet 11 to the compressor rotor 13 is maintained in a raised disposition, as shown in full lines in FIGURE 3, effectively closing the passage 52 while allowing the refrigerant fluid to pass freely through the chamber 51 to pump chamber 14. However, when the flow of refrigerant fluid through the inlet 11 is discontinued, as during a normal compressor shut-down cycle of the refrigeration apparatus, the check valve disc 59 drops downward to rest on the valve seat 58. To positively assure such downward movement, a suitable weight such as ball 60 is provided on the disc 59 in the passage 52.

During normal compressor operation, the refrigerant fluid is conducted from the inlet chamber 51, laterally through channel 61, upwardly through openings 68 and thence into chamber 53, openings 68 communicating with chamber 53 as seen in FIGURE 4. Refrigerant fluid then is conducted from chamber 53 to the suction side of pump chamber 14 via passage 69 within the front head 19. Upon reverse rotation of the compressor, high pressure refrigerant fluid passes from pump chamber 14 through passage 69 into chamber 53 whereupon the valve disc 59 seats itself on valve seat 58 (as shown in broken lines in FIGURE 3) because of the high pressure fluid entering passage 52. At the same time, high fluid pressure is applied to the exterior of bellows 32 causing the bellows to retract, whereupon member 36 lifts movable contact 29 away from contacts 28 and 30 thereby opening switch 37. In this operation, the check valve disc 59 serves to preclude refrigerant fluid flow in the reverse direction through the inlet passage portions 11b and 11a, thereby substantially instantaneously causing a sufficient pressure to actuate the bellows and open switch 37 as discussed above.

The disc 59 and ball weight 60 may be made of a suitable material such as stainless steel. The bellows 32 is preferably formed of a suitable metal material.

Although the use of a check valve disc 59 and ball weight 60 have been shown in the preferred embodiment, it will be readily understood that these elements are not essential to the successful operation of my invention. Then upon reverse rotation of the compresser without the use of disc 59 and weight 60, the pressure within the inlet chamber 51 will, as in the preferred embodiment, exceed the pressure within the interior of the housing to thereby cause termination of compressor operation. Under such conditions, however, the pressure within chamber 51 will not be as great as if the check valve disc were provided and, hence, a more sensitive bellows, that is, a bellows which is responsive to a lower pressure difference between the chamber 51 and housing interior 18, must be used.

Thus, in normal operation, the refrigerant uid flows in the normal manner through the rotor chamber 14 to the discharge conduit 12, switch 37 being normally closed to permit the desired operation. However, if for any reason the direction of rotation of motor 16 is reversed, the presence of pressure in the inlet chamber 51 in excess of dome pressure is immediately sensed by the bel- `lows 32 so as to open switch 37 and substantially instantaneously stop further operation of the motor 16, thereby avoiding either serious damage to the compressor or an undesired loss of cooling at the evaporator surface.

Although the control apparatus 27 is shown herein as embodied in a compressor having a housing subjected to high pressure refrigerant fluid, it will be recognized that this control apparatus is equally adaptable to a compressor having a housing subjected to low pressure refrigerant uid, that is, a so-called low side compressor. In a low side compressor running in the normal direction of rotation, the inlet uid pressure would be equal to or slightly less than the fluid pressure within the housing space. Upon reverse rotation of such a compressor, the fluid pressure within the inlet chamber adjacent the control apparatus 27 is greater than the fluid pressure within the housing space, thus producing a pressure difference relationship identical to that described above for the high side compressor shown in FIGURE 1.

It will be apparent that the control apparatus of this invention, although shown in FIGURE 1 as being mounted within the compressor housing, would function equally as well if it were located externally of the compressor housing. In such a configuration it would only be necessary to provide external connections to the control apparatus 27 such that one side of bellows wall member 31 communicates with the compressor inlet while the other side of this wall member communicates with the housing space 18.

The control apparatus 27 is of particular advantage in the installation of the compressor as it affords the installer a positive indication of the correct connection of the motor 16 to the power supply. Because of the need to manually reset the contactor 40 whenever the contacts 41, 42 and 43 open, the installer will be reminded that the power supply leads have been improperly installed, a fact which he could not otherwise know since the driving motor is sealed within a hermetic housing. Further, the control apparatus 27 provides the above discussed rotation prevention feature fully automatically and, thus, protects the compressor at any time subsequent to its installation in the event that the power supply is reversed. Power supply reversals present a problem in connection with portable equipment using a three-phase power source. It has also been found that in many countries at times phase changes occur in the power supply transmission lines thus calling for the compressor protection afforded by control apparatus 27.

While I have shown and described one embodiment of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In a compressor having a housing, said housing defining a refrigerant fluid space therein, rotary compressor means in said housing, means for rotating said compressor means in a preselected direction of rotation, means defining Ian inlet to said compressor, means for delivering refrigerant fluid thereto during rotation of the compressor means in said preselected direction, means defining an outlet from said compressor means for delivering compressed refrigerant fluid therefrom during rotation of said compressor means in said preselected direction, and means for effectively stopping operation of the compressor in the event of rot-ation opposite to said preselected direction, said stopping means comprising: sensing means in communication with said housing fluid space for sensing the difference between the fluid pressure in said inlet and the fluid pressure in said housing space; and control means responsive to said sensing means for stopping the rotary compressor means in the event said sensing means senses a fluid pressure difference between the fluid pressure in said inlet and the fluid pressure within said housing space indicative of a change in the direction of rotation of said compressor from said preselected direction.

2. In a compressor having a housing, said housing defining a refrigerant fluid space therein, rotary compressor means in said housing, means for rotating said compressor in a preselected direction of rotation, means defining an inlet to said compressor, means for delivering refrigerant fluid thereto during rotation of the compressor means in said preselected direction, means defining an outlet from said compressor means for delivering compressed refrigerant fluid therefrom during rotation of said compressor means in said peselected direction, and means for effectively stopping operation of the compressor in the event of rotation opposite to said preselected direction, said stopping means comprising: means in communication with said housing fluid space for sensing a difference between the fluid pressure in said inlet and the fluid pressure in said housing space; and ycontrol means responsive to said sensing means for stopping the compressor rotating means in the event said sensing means senses a fluid pressure in said inlet greater than the fluid pressure within said housing space.

3. The compressor as cl-aimed in claim 2 including means for preventing reverse refrigerant flow in said inlet upon rotation of said compressor means opposite to said preselected direction.

4. In a compressor las claimed in claim 2, wherein said sensing means comprises a pressure responsive device having a wall movable in response to the pressure differential between said housing space and said inlet.

5. In a compressor as claimed in claim 2, wherein said sensing means comprises a bellows having a wall movable in response to the pressure differential between said housing space and said inlet.

6. In a compressor having a housing, said housing defining a refrigerant fluid space therein, rotary compressor means in said housing, means for rotating said compressor in a preselected direction of rotation, means defining an inlet to said compressor means for delivering refrigerant fluid thereto during rotation of the compressor means in said preselected direction, means defining an outlet from said compressor means for delivering compressed refrigerant fluid to the space defined by said housing during rotation of the compressor means in said preselected direction, and means for effectively stopping operation of the compres-sor in the event of rotation opposite to said preselected direction, said stopping means comprising: means in communication with said housing fluid space for sensing a difference between the fluid pressure in said inlet and the fluid pressure in said housing space; and control means responsive to said sensing means for stopping the means for rotating the compressor in the event said sensing means senses a fluid pressure in said inlet greater than the fluid pressure within said housing space.

7. In a compressor having a housing, said housing defining a refrigerant fluid space therein, rotary compressor means in said housing, mean-s for rotating said compressor in a preselected direction of rotation, means defining an inlet to said compressor means for delivering refrigerant fluid thereto during rotation of the compressor means in said preselected direction, means defining an outlet from said compressor means for delivering compressed refriger-ant fluid to the space defined by said housing during rotation of the compressor means in said preselected direction, and means for effectively stopping operation of the compressor in the event of rotation opposite to said preselected direction, said stopping means comprising: means in communication with said housing fluid space for sensing a difference between the fluid pressure in said inlet and the fluid pressure in said housing space; control means responsive to said sen-sing means for stopping the means for rotating the compressor in the event said sensing means senses a fluid pressure in said inlet greater than the fluid pressure within said housing space; and means for preventing reverse refrigerant flow in said inlet upon rotation of said compressor means opposite to said preselected direction.

8. Ina compressor as claimed in claim 7, wherein said last named means comprises a check valve.

9. In a compressor having a housing, said housing defining a refrigerant fluid space therein, rotary compressor means in said housing, means 'for rotating said compressor in a preselected direction of rotation, means defining an inlet to -said compressor means for delivering refrigerant fluid thereto during rotation of the compressor means in said preselected direction, means defining an outlet from said compressor means for delivering compressed refrigerant fluid to the Ispace defined by said housing during rotation of the compressor means in said preselected direction, means operative upon rotation of the compressor means in said preselected Idirection for lubricating said compressor means, and means for effectively stopping operation of ythe compressor in the event of rotation opposite to said preselected direction, said stopping means comprising:` means in communication with said housing fluid space for sensing a -dilerence between the uid pressure in said inlet -and the fluid pressure in said housing space; and control means responsive to said sensing means for stopping the means -for rotating the compressor in the event said sensing means senses `a fluid pressure in said inlet greater than the uid pressure in said housing space.

References Cited UNITED STATES PATENTS 2,020,485 10/1935 Valkenburg et al. 103-25 X 2,094,807 10/1937 Newill 230-17 2,138,527 10/1938 Mewman 230-42 DONLEY I. STOCKING, Primary Examiner.

W. L. FREEH, Assistant Examiner. 

1. IN A COMPRESSOR HAVING A HOUSING, SAID HOUSING DEFINING A REFRIGERANT FLUID SPACE THEREIN, ROTARY COMPRESSOR MEANS IN SAID HOUSING, MEANS FOR ROTATING SAID COMPRESSOR MEANS IN A PRESELECTED DIRECTION OF ROTATION, MEANS DEFINING AN INLET TO SAID COMPRESSOR, MEANS FOR DELIVERING REFRIGERANT FLUID THERETO DURING ROTATION OF THE COMPRESSOR MEANS IN SAID PRESELECTED DIRECTION, MEANS DEFINING AN OUTLET FROM SAID COMPRESSOR MEANS FOR DELIVERING COMPRESSED REFRIGERANT FLUID THEREFROM DURING ROTATION OF SAID COMPRESSOR MEANS IN SAID PRESELECTED DIRECTION, AND MEANS FOR EFFECTIVELY STOPPING OPERATION OF THE COMPRESSOR IN THE EVEN OF ROTATION OPPOSITE TO SAID PRESELECTED DIRECTION, SAID STOPPING MEANS COMPRISING: SENSING MEANS IN COMMUNICATION WITH SAID HOUSING FLUID SPACE FOR SENSING THE DIFFERENCE BETWEEN THE FLUID PRESSURE IN SAID INLET AND THE FLUID PRESSURE IN SAID HOUSING SPACE; AND CONTROL MEANS RESPONSIVE TO SAID SENSING MEANS FOR STOPPING THE ROTARY COMPRESSOR MEANS IN THE EVENT SAID SENSING MEANS SENSES A FLUID PRESSURE DIFFERENCE BETWEEN THE FLUID PRESSURE IN SAID INLET AND THE FLUID PRESSURE WITHIN SAID HOUSING SPACE INDICATIVE OF A CHANGE IN THE DIRECTION OF ROTATION OF SAID COMPRESSOR FROM SAID PRESELECTED DIRECTION. 